// g2o - General Graph Optimization
// Copyright (C) 2011 R. Kuemmerle, G. Grisetti, W. Burgard
// All rights reserved.
//
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#ifndef G2O_OPTIMIZATION_ALGORITHM_DOGLEG_H
#define G2O_OPTIMIZATION_ALGORITHM_DOGLEG_H

#include <memory>

#include "g2o_core_api.h"
#include "optimization_algorithm_with_hessian.h"

namespace g2o {

class BlockSolverBase;

/**
 * \brief Implementation of Powell's Dogleg Algorithm
 */
class G2O_CORE_API OptimizationAlgorithmDogleg
    : public OptimizationAlgorithmWithHessian {
 public:
  /** \brief type of the step to take */
  enum { STEP_UNDEFINED, STEP_SD, STEP_GN, STEP_DL };

 public:
  /**
   * construct the Dogleg algorithm, which will use the given Solver for solving
   * the linearized system.
   */
  explicit OptimizationAlgorithmDogleg(std::unique_ptr<BlockSolverBase> solver);
  virtual ~OptimizationAlgorithmDogleg();

  virtual SolverResult solve(int iteration, bool online = false);

  virtual void printVerbose(std::ostream& os) const;

  //! return the type of the last step taken by the algorithm
  int lastStep() const { return _lastStep; }
  //! return the diameter of the trust region
  number_t trustRegion() const { return _delta; }

  //! convert the type into an integer
  static const char* stepType2Str(int stepType);

 protected:
  // parameters
  Property<int>* _maxTrialsAfterFailure;
  Property<number_t>* _userDeltaInit;
  // damping to enforce positive definite matrix
  Property<number_t>* _initialLambda;
  Property<number_t>* _lamdbaFactor;

  VectorX _hsd;        ///< steepest decent step
  VectorX _hdl;        ///< final dogleg step
  VectorX _auxVector;  ///< auxilary vector used to perform multiplications or
                       ///< other stuff

  number_t
      _currentLambda;  ///< the damping factor to force positive definite matrix
  number_t _delta;     ///< trust region
  int _lastStep;       ///< type of the step taken by the algorithm
  bool _wasPDInAllIterations;  ///< the matrix we solve was positive definite in
                               ///< all iterations -> if not apply damping
  int _lastNumTries;

 private:
  std::unique_ptr<BlockSolverBase> m_solver;
};

}  // namespace g2o

#endif
